Abstract: Since the data rates in advanced chips dramatically increase, the electrostatic-discharge (ESD) protection circuit at I/O ports causes significant ultrawideband challenges. To address these challenges, an arbitrarily tapped coil (AT-coil) structure with multitaps that enhance bandwidths is proposed; moreover, this structure can also fit into any rectangular layout area to save footprint. A microwave network-assisted analysis approach is proposed concerning the AT-coil, which can better consider the nonideal factors in practical applications and thus converge to a better solution than traditional methods. Further, machine learning-assisted optimization (MLAO) is introduced for designing AT-coil layouts for the first time, and prior human knowledge of high-speed circuits is maximally utilized to speed up MLAO processes. Thus, the converging stability is significantly improved to escape from a local optimum. Additionally, an automatic synthesis example for an on-chip spiral AT-coil proves the capability. Numerical results show that the proposed approach can achieve the best high-frequency performance and guarantee ESD protective robustness.